Dr Foster Intelligence recently published a report that shows a clear association between reduced numbers of senior doctors in hospitals in the United Kingdom and increased mortality at the weekend.1 How should patients, doctors, and commissioners interpret this finding and what can be done to improve patient outcomes at the weekend?

It has been recognised for many years throughout the Western world that mortality is 10% higher in patients admitted to acute hospitals at the weekend than during the week.2 3 Medical conditions, especially cancer and cardiovascular disease,2 account for most of this excess mortality, but increased weekend mortality has also been shown for surgical diagnoses such as ruptured aortic aneurysm.

The Dr Foster report compared hospital standardised mortality ratios (HSMRs) for patients admitted to English hospital trusts on two weekends in April 2011 with those admitted in the week. They then used self reported data on staffing levels from hospitals to assess the effect of numbers of doctors—both resident and on-call—on weekend mortality. Data were collected on all grades of doctor (and nurses), but interestingly only the number of senior doctors (registrars and consultants) was associated with a difference in weekend mortality.

The hypothesis that early assessment and intervention by experienced clinicians results in improved weekday mortality seems to be a …